About two dozen employees have been working since last year to try and figure how to take Aramco public, and have been working with Western consultants to explore ways to restructure Aramco to maximize its value, say people familiar with the process. The team has determined several variables – or what some call “levers” – likely to affect the price investors will pay for shares of the world’s largest oil producer, according to internal documents reviewed by The Wall Street Journal and people familiar with the process.

But, as The Wall Street Journal reports,no matter how they pull those levers, which include the price of oil and Saudi tax policy, Aramco’s projected value tops out at about $1.5 trillion, these people say.

One such lever was a major tax reduction (but even then it didn't add up to bin Salman's $2 trillion guess…

The Saudi government last month said it is reducing Aramco’s tax rate to 50% from 85%, bringing its tax rate closer to the level of the world’s biggest oil companies such as Exxon Mobil and Royal Dutch Shell.

That move would result in higher dividends for potential shareholders, and it brought Aramco’s internal value estimates to $1.3 trillion to $1.5 trillion from about half a trillion dollars, say people involved in the process.

By selling up to 5% of shares in an initial public offering targeted for next year, the government plans to raise billions of dollars that it can use to invest in other industries as part of a plan to reduce its heavy dependence on oil. The valuation discrepancy raises new challenges for a deal that is already fraught with complexity and facing opposition within the ranks of the kingdom’s government bureaucracy, according to people familiar with the matter.

One Aramco official called the figure “unrealistic and mind blowing.”

Questions about Aramco’s valuation surfaced earlier this year when a report for potential investors prepared by oil-industry consultant Wood Mackenzie Ltd. put Aramco’s value at around $400 billion, according to a client who attended a private Wood Mackenzie briefing. Saudi government officials say Aramco’s high reserves and low costs should make the company attractive to investors.

“Our profitability is higher than others and the interest we have received so far is huge,” said one official who defended the $2 trillion number.

Some officials inside the company and in government have privately suggested reevaluating the listing, say people familiar with the matter, and perhaps reducing its size or delaying it. So far, Prince Mohammed and his staff seem unlikely to do so, say people familiar with the matter.

“This IPO will happen regardless of the valuation they may receive,” according to the government official who called the $2-trillion-dollar number “mind-blowing.”